1. Field of Invention
The present invention relates to a fan of an electronic apparatus, and more particularly, to a wind guiding cover capable of self-closing when the fan is not in operation.
2. Related Art
Along with an increasing processing speed of computer equipments, thermal-dissipation issues due to the long-time operation of electronic parts therein will occur, and directly affect the performance and stability of the computer equipments. Therefore, how to quickly dissipate the waste thermal generated by the electronic parts so as to improve the thermal-dissipation efficiency has become the toughest problem in the industry during recent years. In the commonly adopted thermal-dissipation methods, an electronic part in need of improving the thermal-dissipation effect is inevitably added with a thermal-dissipation module constituted by heatsink fin sets, heat pipes, fans, and the like, and then the system fan of the computer host exhausts the waste thermal out of the case, so as to lower the temperature in the computer host.
As for industrial computers and servers, a large number of electronic parts are disposed within the hosts and are densely arranged, so the requirements on thermal dissipation are higher than those ordinary computer equipments. In addition, since the arrangement of the electronic parts is quite compact, the flow resistance against the air flows within the hosts is large. Therefore, the number of fans disposed in the hosts of the industrial computers or servers is greater than that of the ordinary computer equipments. Moreover, in the prior art, in order to increase the flux of the thermal-dissipation air flows to overcome the flow resistance, a plurality of fans is disposed side by side. For example, the fans are first fixed to a frame side by side, and then fixed to the host case with the frame.
However, when the fans are arranged side by side, as long as one of the fans stops operating due to damage or failure, the air flow may flow back from the gap of the failed fan under pressure difference. That is, the air will flow from the air-outlet side back to the air-inlet side via the failed fan, so that the flow field becomes unstable, thus affecting the flow rate and flux of the air flow. When the flow rate and flux of the air flow passing through the electronic parts are reduced, the thermal-dissipation efficiency of the electronic parts will certainly be alleviated. As a result, the waste thermal generated by the operation of the electronic parts cannot be successfully dissipated, and will be accumulated within the computer host case. Therefore, with the power-on operation of the computer, the temperature in the case continuously rises due to poor convection, thus weakening the performance and stability of the computer equipment, or even resulting in damages to the computer equipment under a high temperature.
In order to solve the problem that the air flow field of the densely arranged fans in the server is interfered, a design has been proposed in this industry to add louver slats to the fan or fan board. Such louver slats can be closed when the fan fails to operate so as to prevent the flow field being interfered. However, the conventional louver slats have to be manually opened or closed, and are inconvenient in use. In addition, some louver slats may be lifted by the air flow when the fan operates and closed under the gravity when the fan stops. Moreover, the fans are fixed on a mobile rack of the server, and the mobile rack may be placed on the server transversely or in an upright manner. Therefore, when the mobile rack is transversely placed, the louver slats can certainly be successfully closed when the fan stops. However, when the mobile rack is placed in an upright manner, the louver slats cannot be successfully closed, and the thermal-dissipation efficiency will be affected.